Ability Keywords: Class features have ability keywords (such as [Martial], [Psychic], or [Lore]). Certain feats alter abilities related to those keywords, and prestige classes advance features with specific keywords that also have the [Progressing] keyword.

Color-Coded For Your Convenience: Dragons will no longer be color-coded, instead using an assembly system similar to the cataclysm's. Retaining metallic/chromatic is up in the air.

Elements: Elements are acid, cold, electricity, entropic, fire, radiant, and sonic. Positive and negative energy are gone, and all creatures are affected by all energies unless explicitly called out as a per-monster resistance or immunity.

Elemental Damage and Resistances: Elemental resistances are measured per-die (so Fire Resist 1 means that a 5d6 fireball deals 5d6-5 to you; Fire Resist 4 [relatively uncommon] means that a 20d6 fireball deals 20d6-80 damage to you). Elemental damage, similarly, receives benefits on a per-die basis: Empower Spell, for instance, increases damage by 2 per die. Resist 6 is fiat-immunity, surpassed only ineffectively by high-intensity energy (example: an azer may have Fire Resist 6. This makes him immune to regular fire, but a pyromancer's fireball might have +4 or +5 per die. If the pyromancer hits the azer with a 15d6 (+5) fireball, the azer takes 15d6-90+75, or 15d6-15. Similarly, a remorhaz (fire resist 3) hit by a 10d6 (+7) fireball would take 10d6-30+70, or 10d6+40.).

Favored Classes and Multiclass Feats: Races have one or two favored classes: for the specified classes, they substitute 1/2 their class level plus their Hero Value for class level for [Progressing] features from the specified class if they have at least three levels in the specified class. Multiclass feats work similarly: they progress any class feature with the correct keyword and the [Progressing] keyword at 1/2 class level plus Hero Value in place of their class level.

Gods:The gods (provided with the cleric) do not have associated alignments. This is intentional.

Hero Value: Hero Value is equal to half your level, rounded up. Many effects are based on your Hero Value. You add your Hero Value to your Armor Class in the same fashion you add a Natural Armor bonus--it is not natural armor, it just applies at the same time. Feats with the [Heroic] descriptor have varying effects based on your Hero Value. Save DCs for spellcasting and class features may be altered to be a global 10+HV+Mod mechanic.

Leveling Up: At every level evenly divisible by 2, you gain a feat. Every time you gain a level in a class evenly divisible by 3, you gain a bonus feat. At every level evenly divisible by 4, you increase two statistics by 1.

Monster Stat Block: The monster stat block has been revised for clarity and ease of use, as seen here.

Negative Levels: Negative levels have been removed. In their place is Hero Value damage (as seen on the succubus). If your Hero Value drops below 0, you lose all class features and invested prowess until it returns to positive values.

Poison: Poison no longer inflicts ability damage (or at least, not in every instance). It instead inflicts ongoing damage every round for a set number of rounds. Additional poisoning attacks reset the remaining duration. This creature has an example venom.

Prowess: Each class gains between 2 to 6 prowess per level (exception: the dreadnaught gains 6 per level and gains an additional 2 per level from a class feature). Prowess is immediately invested into feats (specifically, feats with the [Investing] descriptor) to augment their effects. Many basic martial feat chains have been condensed into single [Investing] feats, so as to decrease the amount of 'feat taxes' in the game and decrease the opportunity cost of certain styles of play. An Investing feat cannot have more prowess invested in it than your BAB+3. Prowess can also be invested into Style Feats (see below) and weapon proficiencies (see below).

Races and Racial Feats: Races have a 'racial charge' mechanic in most cases (exception: goblins have a different mechanism). They receive a number of charges equal to one-third their level, plus one, plus one for each racial feat they possess. Most racial feats are powered by racial charges.

Skills: Skills use a training mechanism instead of skill points. Each class gains a number of "skill sets" which determine what skills you are trained in: most classes receive at least one variable skill set with which they can alter their skill list somewhat. You also are trained in an additional number of skills equal to your Intelligence modifier. Having a skill in one of your skill sets trains you as an apprentice. Overlapping a skill in two or more skill sets trains you as a Journeyman and opens special skill functions. The Skill Mastery class feature (and potentially other sources as well) trains you as a Master and opens up advanced special functions.

Spellcasting: Prepared spellcasting (like the 3.5 wizard) is gone. The closest analogue (and what the wizard will be using) is the style of prepared spontaneity the paladin uses.

Status Conditions: Immobilized is now a status condition. An immobilized creature cannot move from his current square, but is still able to defend himself. An immobilized flying creature stalls (unless they have Perfect maneuverability or the Hover feat), falling at 150' in the first round and 300' the second round, and lands in the square it was over when immobilized.

Style Feats: Style feats are like Investing feats in that they act as a receptacle for Prowess. However, instead of providing a single, scalar ability like most Investing, Style feats provide trees of benefits: you must purchase abilities in the order of the tree. Many combative classes provide Style feats at 2nd or 3rd level. A Style feat's maximum prowess invested is your BAB*6.

Variable Monsters: Important, difficult, iconic, or intrinsically dynamic monsters have variable attributes (example: dragons and cataclysms). This increases the mystery surrounding important and iconic monsters and helps prevent metagaming for important combats. While this does increase DM responsibility and effort, the end result is worthwhile in my opinion, and including some pre-made variable monsters with the statistic block allows for quick play.

Weapon Proficiencies: Weapon proficiencies are based off of the Weapon Group Proficiencies variant from Unearthed Arcana. There is no difference between a simple, martial, or exotic weapon anymore. These have not been ported to this forum as of 1/18/2011.

I love that feats are not nearly as scarce, and they're a built in incentive to not multi-class, or even take a PrC. That said there may be some PrCs that are close enough in line with their intended entry class that they could stack for feat purposes.

On Hero Value - I see the logic in having it set up as DragoonWraith proposes, but the only confusing part I see is that pretty much everything else is always rounded down.

The favored class change is awesome. Great way to make the restriction relevant!